Clarify in text the relationship to Trace Context

[pes10k]

This issue is a result of the PING review requested here: w3cping/privacy-request#94

It wasn't clear to me the relationship between Baggage and Trace Context rec, also from the Distributed Tracing Working Group. They seem very similar, both in targeted use cases and (only slightly less so) technique. It would be very helpful for the reader to say explicitly in text how these two specs/proposals relate.

For example, is Baggage intended to replace Trace Context? Augment it? Define some in-the-work super set of functionality that a future Trace Context will fit into? etc?

This is also important bc Trace Context makes more specific privacy-relevant demands / requests on the implementor (for example, Sec 6.1. says "Random number generators MUST NOT rely on any information that can potentially be user-identifiable", Sec 6.2. says "Vendors MUST NOT include any personally identifiable information in the tracestate header.", etc.

[kalyanaj]

Thanks @pes10k. I have created the above PR towards this issue (need to discuss with the rest of the WG members on whether this is the right place to add this difference or if there's a better place). Meanwhile, you may want to check out https://github.com/w3c/baggage/blob/main/baggage/README.md that describes a few example use-cases for Baggage. It is independent of Trace Context (which is for enabling distributed tracing).